Text Scrolling

Hello
I’ve made a simple Chat-System but I really don’t know how to add Scrolling,
Here is my Code:

using UnityEngine;
using System.Collections;

public class Chat : MonoBehaviour
{
    public GUISkin myskin;
  
    private Rect windowRect = new Rect(0,Screen.height - 400, Screen.width, 400);

    private string messBox = "", messageToSend = "", user = "";

    private int ID;

    private Inventory MyInventory = new Inventory ();
    private PlayerSkin MyPlayerSkin = new PlayerSkin();

    private bool Send;
    private bool AdminMode;

    private Texture2D otherSkin;
    private Sprite mysprite;
    private bool ChatVisible;

    Vector2 scrollPosition;
    void Start()
    {
        user = PlayerEssentials.PlayerName;
        //otherSkin = Resources.Load<Texture2D> ("Skins/PlayerBase");
    }
    private void OnGUI()
    {
        GUI.skin = myskin;
        if (NetworkPeerType.Disconnected != Network.peerType && ChatVisible)
        {
                windowRect = GUI.Window (1, windowRect, windowFunc, "", myskin.GetStyle ("ChatWindowStyle"));
        }
    }
    void Update()
    {
        if (Input.GetKeyDown (KeyCode.T)) //dodanie else sprawi jednorazowe działanie;
        {
            ChatVisible = !ChatVisible;
        }
    }

    [RPC]
    private void windowFunc(int id)
    {

        GUILayout.Box(messBox,GUILayout.Height(350));

        GUILayout.BeginHorizontal();
  

        messageToSend = GUILayout.TextField(messageToSend);
        GUILayout.EndHorizontal ();
        GUILayout.BeginVertical ();

      
        if (Input.GetKeyDown(KeyCode.T) || Input.GetKeyDown(KeyCode.F))
        {
            if(user != "")
            {
            if(messageToSend.Contains("//"))
            {
                // Tutaj tworzymy Komendy
                if(messageToSend == "//test")
                {
                    networkView.RPC("SendMsg", RPCMode.All,"<color=#00a2ff>" + "Wszystko jest w porządku" + "</color>" + "\n");
                    messageToSend = "";
                }
                else if(messageToSend == "//inventory clear" && AdminMode)
                {
                        MyInventory.ClearInventory ();
                        messageToSend = "";
                }
                else if(messageToSend.StartsWith("//item add ") && AdminMode)
                {
                        string d = (messageToSend.Replace("//item add ",""));
                        MyInventory.database = GameObject.FindGameObjectWithTag("Item Database").GetComponent<ItemDatabase>();
                        MyInventory.AddItem(int.Parse (d));
                        messageToSend = "";
                }
                    else if(messageToSend.StartsWith("//item remove ") && AdminMode)
                    {
                        string d = (messageToSend.Replace("//item remove ",""));
                        MyInventory.database = GameObject.FindGameObjectWithTag("Item Database").GetComponent<ItemDatabase>();
                        MyInventory.RemoveItem(int.Parse (d));
                        messageToSend = "";
                    }
                    else if(messageToSend == "//chat clear" && AdminMode)
                    {
                        messBox = "";
                        messageToSend = "";
                    }
                else if(messageToSend == "//adminmode on emiltokomputer")
                    {
                        AdminMode = true;
                        messageToSend = "";
                    }
                    else if(messageToSend == "//adminmode off" && AdminMode)
                    {
                        AdminMode = false;
                        messageToSend = "";
                    }
                    else if(messageToSend.StartsWith("//speed me ") && AdminMode)
                    {
                        string d = (messageToSend.Replace("//speed me ",""));
                        PlayerEssentials.speed = float.Parse(d);
                        messageToSend = "";
                    }
                    else if(messageToSend == "//invisible on" && AdminMode)
                    {
                        PlayerEssentials.spriteRenderer.sprite = new Sprite();

                    }
                    else if(messageToSend.StartsWith("//skin change ") && AdminMode)
                    {
                        string d = (messageToSend.Replace("//skin change ",""));
                        otherSkin = Resources.Load<Texture2D>("Skins/" + d);
                        PlayerEssentials.spriteRenderer.sprite = Sprite.Create(otherSkin,new Rect(0,0,otherSkin.width,otherSkin.height),new Vector2(0.5f,0.5f));
                        messageToSend = "";
                        //string d = (messageToSend.Replace("//skin change ",""));
                        //MyPlayerSkin.skinDatabase = GameObject.FindGameObjectWithTag ("Skin Database").GetComponent<SkinDatabase>();
                    //    MyPlayerSkin.ChangeSkin(int.Parse (d));


                    }
                else
                {
                    networkView.RPC("SendMsg", RPCMode.All,"<color=#ff8400>" + "Emil nie mógł znaleźć tej komendy!" + "</color>" + "\n");
                    messageToSend = "";
                }
              

            }
            else
            {
                    if(messageToSend != "")
                    {
                    networkView.RPC("SendMsg", RPCMode.All, user + ": " + "<color=#00a2ff>" + messageToSend + "</color>" + "\n");
                    messageToSend = "";
                    }
                    else
                    {
                  
                    }
            }
            }

            if(messageToSend == "")
            {
                Send = false;
            }
            else
            {
                Send = true;
            }
        }
  
        GUILayout.EndVertical();
    }
    [RPC]
    private void SendMsg(string mess)
    {
        messBox += mess;

    }
}

Can anyone tell me how to do this ?

Have you looked at the tutorials for UI Scroll Rect and UI Scrollbar?

Yes but I still don’t know how to add these to my Chat without changing everything (I really don’t want to destroy my actual Chat).

Oh, you’re using OnGUI. Sorry, I can’t help you there.